Sample apertures weight

Table 9 shows the results of the sieve analysis obtained for a sample of a FCC1 powder. The values reported in the first two columns of the table are the standard diameters of the sieve apertures. From these the mean diameter dp is obtained for each two adjacent sieve sizes and the values are reported in the third column. From the mass fraction of powder in each sieve (values in the fourth column) the weight percentage is obtained and reported in the fifth column. Thus, the sum of the mass fraction over the mean diameter allows the calculation of the volume-surface mean particle diameter of the distribution using Equation (1) ... 

Coarse Particles Add 100 mL of water to 20 g of sample, and mix for 15 min at not less than 5000 rpm. Transfer the mixture to a wet sieve of nominal mesh aperture (75 p,m), previously dried at 100° to 105° and weighed, and wash with three 500-mL volumes of water, ensuring that any agglomerates are dispersed. Dry at 100° to 105°, and weigh. The difference in weight corresponds to the measure of coarse particles. 

ASTM standard " is similar to ISO standard but it is not its technical equivalent. The main differences include samples thickness (0.25 mm in ASTM and 1 mm in ISO), activated carbon size (1.4 mm in ASTM and 4 to 6 mm in ISO), gauze apertures (0.595 mm in ASTM and 0.5 mm in ISO), and container sizes. Different activated carbon grades give different results. According to ASTM standard percent of weight loss is an inverse function of sample thickness. 

The loss of mass (Mi) is determined as a percentage by weight of the initial sample after sieving through a sieve having an aperture of half the lower nominal size. 

Consulting the British Standards Screen Scale in Appendix 5, the nominal aperture sizes in micrometers are tabulated versus the weight retained. Then, the fractions retained on each of the sieves used in the test can be listed as percentage of the original test sample weight, and finally as the oversize cumulative percentages (i.e., running totals). The results of these calculations can be tabulated on a second table (Table 2.8). 

The content of coarse particles is determined as the residue retained on the test sieve with 0.2 mm aperture size (DIN 4188, Sheet 1) by manual or mechanical sieving. The sample for the sieve test should consist of 100 0.100 g of dry cement. Sieving is stopped when the residue does not decrease by more than 0.1 % on continuation of sieving for a further 2 minutes. The amount retained on the sieve is stated in % by weight, referred to the initial sample. 

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